Turn off font smoothing in SeaMonkey for Windows

I'm running SeaMonkey on Windows 8.1, and I have recently upgraded to version 2.40.

Although I have full-pixel AA and ClearType disabled entirely (which can be seen either by running systempropertiesadvanced.exe/cttune.exe or looking at simple MFC apps appearance), SeaMonkey still anti-aliases fonts -- both in the web pages and in its UI.

I've already seen the same question for Firefox 4, so I made the following changes to my prefs.js:

• Set gfx.direct2d.disabled to true
• Set gfx.use_text_smoothing_setting to true (yes I'm aware it's Mac OS X-specific, but I gave it a try anyway)
• Set gfx.font_rendering.directwrite.enabled to false (this property was last available in 2.39 and is gone in 2.40, so I assume it may be no longer effective -- but I added it just in case).

No luck so far.

Then I downloaded Anti-Aliasing Tuner add-on, made it compatible with SeaMonkey (for some reason, Firefox 43 personality in the User Agent string wasn't enough), installed it and set font rendering to "Aliased" wherever appropriate:

This resulted in the following extra preferences set:

extensions.aatuner.large.aamode = 3
extensions.aatuner.small.aamode = 3
extensions.aatuner.large.rdmode = 1
extensions.aatuner.small.rdmode = 1
gfx.font_rendering.cleartype_params.rendering_mode = 1

(it looks gfx.font_rendering.cleartype_params.rendering_mode just takes the same value as extensions.aatuner.*.rdmode).

Despite the above efforts, SeaMonkey still renders my fonts antialiased (and yes, I've restarted the browser multiple times).

How the heck do I turn AA off?

Update #1: for SeaMonkey 2.40 running on Windows XP, the same combination of settings gives perfect crisp aliased fonts (full-pixel AA and ClearType are disabled system-wide).

Update #2: SeaMonkey essentially uses full-pixel AA (meaning ClearType is off) -- see the screenshot below. Now, the only browsers that still can display aliased text on my Windows box are Opera and Safari.

Update #3: starting SeaMonkey in safe mode does turn AA off. This is equivalent to un-checking "Use hardware acceleration when available" under Preferences -> Appearance -> Content. Clearing this flag actually sets both gfx.direct2d.disabled and layers.acceleration.disabled to true, while for aliased fonts display layers.acceleration.disabled=true alone is sufficient (and, as mentioned above, gfx.direct2d.disabled has no effect at all). Still, I would like some explicit preference for font display control, without the need to turn HW acceleration entirely.

Update #4: playing with Anti-Aliasing Tuner parameters only makes sense if at least full-pixel font smoothing (systempropertiesadvanced.exe -> Advanced -> Performance -> Visual Effects -> Smooth edges of screen fonts) is turned on in Windows. In this case, ClearType and Greyscale modes yield more blurred text than the Aliased mode (which can be called "almost aliased").